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Gwen Noda

Galaxy Zoo Volunteers Share Pain and Glory of Research - 0 views

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    Science 8 July 2011: Vol. 333 no. 6039 pp. 173-175 Galaxy Zoo Volunteers Share Pain and Glory of Research 1. Daniel Clery A project to "crowdsource" galactic classifications has paid off in ways the astronomers who started it never expected. Figure View larger version: * In this page * In a new window Space oddity. Greenish "voorwerp" spotted by a Dutch volunteer still intrigues scientists. "CREDIT: NASA, ESA, W. KEEL (UNIVERSITY OF ALABAMA), AND THE GALAXY ZOO TEAM" The automated surveys that are becoming increasingly common in astronomy are producing an embarrassment of riches for researchers. Projects such as the Sloan Digital Sky Survey (SDSS) are generating so much data that, in some cases, astronomers don't know what to do with them all. SDSS has compiled a list of more than 1 million galaxies. To glean information about galaxy evolution, however, astronomers need to know what type of galaxy each one is: spiral, barred spiral, elliptical, or something else. At present, the only reliable way to classify galaxies is to look at each one. But the SDSS list is so long that all the world's astronomers working together couldn't muster enough eyeballs for the task. Enter the "wisdom of crowds." An online effort called Galaxy Zoo, launched in 2007, set a standard for citizen-scientist participation projects. Zealous volunteers astonished the project's organizers by classifying the entire catalog years ahead of schedule. The results have brought real statistical rigor to a field used to samples too small to support firm conclusions. But that's not all. Buoyed by the curiosity and dedication of the volunteers, the Galaxy Zoo team went on to ask more-complicated classification questions that led to studies they hadn't thought possible. And in an online discussion forum on the Galaxy Zoo Web site, volunteers have pointed to anomalies that on closer inspection have turned out to be genuinely new astronomical objects. "I'm incredibly impres
Gwen Noda

The Ten Best Ocean Stories of 2012 | Surprising Science - 0 views

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    December 18, 2012 The Ten Best Ocean Stories of 2012 | | | Share on redditReddit | Share on diggDigg | Share on stumbleuponStumble | Share on emailEmail | More Sharing ServicesMore Two market squids mating 2012 was a big year for squid science. Photo Credit: © Brian Skerry, www.brianskerry.com Despite covering 70 percent of the earth's surface, the ocean doesn't often make it into the news. But when it does, it makes quite a splash (so to speak). Here are the top ten ocean stories we couldn't stop talking about this year, in no particular order. Add your own in the comments! 2012: The Year of the Squid From the giant squid's giant eyes (the better to see predatory sperm whales, my dear), to the vampire squid's eerie diet of remains and feces, the strange adaptations and behavior of these cephalopods amazed us all year. Scientists found a deep-sea squid that dismembers its own glowing arm to distract predators and make a daring escape. But fascinating findings weren't relegated to the deep: at the surface, some squids will rocket themselves above the waves to fly long distances at top speeds. James Cameron Explores the Deep Sea Filmmaker James Cameron has never shied away From marine movie plots (See: Titanic, The Abyss), but this year he showed he was truly fearless, becoming the first person to hit the deepest point on the seafloor (35,804 feet) in a solo submarine. While he only managed to bring up a single mud sample From the deepest region, he found thriving biodiversity in the other deep-sea areas his expedition explored, including giant versions of organisms found in shallow water. Schooling sardines form a "bait ball." Small fish, such as these schooling sardines, received well-deserved attention for being an important part of the food chain in 2012. Photo Credit: © Erwin Poliakoff, Flickr Small Fish Make a Big Impact Forage fish-small, schooling fish that are gulped down by predators-should be left in the ocean for larger fish, marin
Gwen Noda

Time to Adapt to a Warming World, But Where's the Science? - 0 views

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    "Science 25 November 2011: Vol. 334 no. 6059 pp. 1052-1053 DOI: 10.1126/science.334.6059.1052 * News Focus Adaptation to Climate Change Adaptation to Climate Change Time to Adapt to a Warming World, But Where's the Science? 1. Richard A. Kerr With dangerous global warming seemingly inevitable, users of climate information-from water utilities to international aid workers-are turning to climate scientists for guidance. But usable knowledge is in short supply. Figure View larger version: * In this page * In a new window Adapt to that. Climate will change, but decision-makers want to know how, where, and when. "CREDIT: KOOS VAN DER LENDE/NEWSCOM" DENVER, COLORADO-The people who brought us the bad news about climate change are making an effort to help us figure out what to do about it. As climate scientists have shown, continuing to spew greenhouse gases into the atmosphere will surely bring sweeping changes to the world-changes that humans will find it difficult or impossible to adapt to. But beyond general warnings, there is another sort of vital climate research to be done, speakers told 1800 attendees at a meeting here last month. And so far, they warned, researchers have delivered precious little of the essential new science. At the meeting, subtitled "Climate Research in Service to Society,"* the new buzzword was "actionable": actionable science, actionable information, actionable knowledge. "There's an urgent need for actionable climate information based on sound science," said Ghassem Asrar, director of the World Climate Research Programme, the meeting's organizer based in Geneva, Switzerland. What's needed is not simply data but processed information that an engineer sizing a storm-water pipe to serve for the next 50 years or a farmer in Uganda considering irrigating his fields can use to make better decisions in a warming world. Researchers preparing for the next international climate assessment, due in 2013, delive
Gwen Noda

Bounds and Vision - 0 views

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    Information Science Bounds and Vision Atlas of Science Visualizing What We Know by Katy Börner MIT Press, Cambridge, MA, 2010. 266 pp. $$29.95, £22.95. ISBN 9780262014458. 1. Mason A. Porter + Author Affiliations 1. The reviewer is at the Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford OX1 3LB, UK, and at the CABDyN Complexity Centre and Somerville College, University of Oxford. 1. E-mail: porterm@maths.ox.ac.uk Visualization is a crucial but underappreciated part of science. As venues like the American Physical Society's Gallery of Fluid Motion and Gallery of Nonlinear Images illustrate every year, good visuals can make science more beautiful, more artistic, more tangible, and often more discernible. Katy Börner's continuing exhibition Places & Spaces: Mapping Science (1) and her book Atlas of Science: Visualizing What We Know arise from a similar spirit but are much more ambitious. Visualization is one of the most compelling aspects of science. Breathtaking visuals from sources like fractals and Disneyland's long-dead "Adventure Thru Inner Space" ride are what originally inspired me toward my personal scientific path, so I welcome any resource that promises to bring the visual joys of discovery to a wide audience. Importantly, Börner's exhibition and book are not mere artistic manifestations, although they would be impressive accomplishments even if that were her only goal. Some scientists have occasionally had great success in the visual arts; for example, physicist Eric Heller has long exhibited the gorgeous fruits of his research on quantum chaos and other topics (2). To fully appreciate Börner's efforts, however, one must be conscious that she is deeply concerned not just with visualization itself but with the science of visualization. Accordingly, her book discusses the history of the science of visualization, where it is now, and where she thinks it can go. Atlas of Scie
Gwen Noda

Humans Are Driving Extreme Weather; Time to Prepare - 0 views

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    "Science 25 November 2011: Vol. 334 no. 6059 p. 1040 DOI: 10.1126/science.334.6059.1040 * News & Analysis Climate Change Humans Are Driving Extreme Weather; Time to Prepare 1. Richard A. Kerr Figure View larger version: * In this page * In a new window Thai floods 2011 Hurricane Katrina 2005 Texas drought 2011 "CREDITS (LEFT TO RIGHT): PAULA BRONSTEIN/GETTY IMAGES; JEFF SCHMALTZ, MODIS RAPID RESPONSE TEAM, NASA/GSFC; NOAA" An international scientific assessment finds for the first time that human activity has indeed driven not just global warming but also increases in some extreme weather and climate events around the world in recent decades. And those and likely other weather extremes will worsen in coming decades as greenhouse gases mount, the report finds. But uncertainties are rife in the still-emerging field of extreme events. Scientists cannot attribute a particular drought or flood to global warming, and they can say little about past or future trends in the risk of high-profile hazards such as tropical cyclones. Damage from weather disasters has been climbing, but the report can attribute that trend only to the increasing exposure of life and property to weather risks. Climate change may be involved, but a case cannot yet be made. Despite the uncertainties, the special report from the Intergovernmental Panel on Climate Change (IPCC) released 18 November stresses that there is still reason for taking action now. The panel recommends "low-regrets measures," such as improvements in everything from drainage systems to early warning systems. Such measures would benefit society in dealing with the current climate as well as with almost any range of possible future climates. The report takes a cautious, consensus-based approach that draws on the published literature. Headlines and even some scientists may point to the current Texas drought or the 2003 European heat wave as the result of the strengthening greenhouse. But the report fin
Gwen Noda

Communicating and Learning About Global Climate Change - 1 views

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    Table of Contents About Science for All Americans and Atlas of Science Literacy.................................................. 4 From Chapter 1: The Nature of Science ............................... 5 From Chapter 3: The Nature of Technology ......................... 7 Map: Scientifi c Investigations ............................................. 11 Map: Interaction of Technology and Society ..................... 13 Map: Decisions about Using Technology ........................... 15 From Chapter 4: The Physical Setting ............................... 16 Recommended Reading ..................................................... 17 Map: Weather and Climate .................................................. 19 Map: Use of Earth's Resources ............................................ 21 From Chapter 8: The Designed World ................................ 22 From Chapter 5: The Living Environment .......................... 23 Map: Energy Resources ...................................................... 25 Map: Interdependence of Life ............................................ 27 Recommended Reading ..................................................... 28 Web Sites for Climate Change Resources ........................... 29
Gwen Noda

Know Your Ocean | Science and Technology | Ocean Today - 0 views

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    NARRATOR: Even though the ocean covers seventy percent of the Earth's surface, people tend to know more information about land than the sea. As a result, our understanding of the ocean is often incomplete or full of misconceptions. How well do you know the ocean? You may think Earth has five separate oceans. They're clearly labeled on our maps. But, in actuality, these are all connected, and part of one global ocean system. Ever wonder why the ocean is blue? You may have heard its because the water reflects the color of the sky. Not quite. Sunlight contains all the colors of the rainbow. When it hits the ocean, it gets scattered by the water molecules. Blue light is scattered the most, which is why the ocean appears blue. Even more interesting is that floating plants and sediments in the water can cause light to bounce in such a way for the ocean to appear green, yellow, and even red! Another idea some people have is that the sea floor is flat. Actually, just like land, the sea floor has canyons, plains, and mountain ranges. And many of these features are even bigger than those found on land. You may also think that our ocean's saltwater is just a mix of water and table salt. Not so. Seawater's "salt" is actually made of dissolved minerals from surface runoff. That is, excess water from rain and melting snow flowing over land and into the sea. This is why the ocean doesn't have the same level of salinity everywhere. Salinity varies by location and season. Finally, you may have heard that melting sea ice will cause sea levels to rise. In reality, sea ice is just frozen seawater, and because it routinely freezes and melts, its volume is already accounted for in the ocean. Sea levels can rise, however, from ice that melts off land and into the ocean. Understanding basic facts about the ocean is important since it affects everything from our atmosphere to our ecosystems. By knowing your ocean, you are better prepared to help protect it.
Gwen Noda

The Southern Ocean's Role in Carbon Exchange During the Last Deglaciation - 0 views

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    Abstract Changes in the upwelling and degassing of carbon from the Southern Ocean form one of the leading hypotheses for the cause of glacial-interglacial changes in atmospheric carbon dioxide. We present a 25,000-year-long Southern Ocean radiocarbon record reconstructed from deep-sea corals, which shows radiocarbon-depleted waters during the glacial period and through the early deglaciation. This depletion and associated deep stratification disappeared by ~14.6 ka (thousand years ago), consistent with the transfer of carbon from the deep ocean to the surface ocean and atmosphere via a Southern Ocean ventilation event. Given this evidence for carbon exchange in the Southern Ocean, we show that existing deep-ocean radiocarbon records from the glacial period are sufficiently depleted to explain the ~190 per mil drop in atmospheric radiocarbon between ~17 and 14.5 ka.
Gwen Noda

UnderwaterTimes.com | Ocean Probes To Help Refine Climate Change Forecastin - 0 views

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    Ocean Probes To Help Refine Climate Change Forecasting; 'Oceanography Is Risky; You Lose Things' by Underwatertimes.com News Service - August 5, 2011 17:43 EST LOS ANGELES, California -- A USC researcher has opened a new window to understanding how the ocean impacts climate change. Lisa Collins, environmental studies lecturer with the USC Dornsife College, spent four years collecting samples from floating sediment traps in the San Pedro Basin off the Los Angeles coast, giving scientists a peek at how much carbon is locked up in the ocean and where it comes from. Collins' research suggests that the majority of particulate organic carbon (POC) falling to the basin floor is marine-derived, not the result of runoff from rainfall. This means that the ocean off the coast of Southern California is acting as a carbon "sink" - taking carbon out of the atmosphere via phytoplankton and locking it up in sediment. Though estimates regarding the effect of carbon in the ocean already exist, her hard data can help climatologists create more accurate predictions of how carbon will impact global warming. What is unique about Collins' study is that it is not just a snapshot of POC falling, but rather a finely detailed record of four years of POC production, showing how much fell and when. "It's all tied to climate change," said Collins, who started the research as a graduate student working for USC Earth Sciences Professor Will Berelson. "This lets us see patterns. "Our data can help climate modelers better predict the interactions between the oceans and atmosphere with respect to carbon which can help them better predict how much carbon dioxide will end up sequestered over the long term as sediments in the ocean," she said. Collins' study is among the longest of its kind in the region. A similar study was conducted in Santa Monica Basin from 1985-1991, and another is currently underway in Hawaii. Her findings appear in the August issue of Deep-Sea Research I. Between Janua
Gwen Noda

Webcast: 'We Sea Change,' a Climate Change Education Video | The Ocean Portal | Smithsonian Institution - 0 views

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    Webcast: 'We Sea Change,' a Climate Change Education Video 0 What is climate change, and how is it affecting coastal Carolina? That is the question that a group of teens from Isaac Bear Early College High School set out to answer for their Third National Student Summit on the Ocean & Coasts project. Representing the North Carolina Aquarium at Fort Fisher, four teens spent months researching climate change issues such as salt water intrusion in rivers, changes to barrier islands, disappearing beaches, and habitat loss in longleaf pine forests in the Wilmington, N.C., region. The students presented a video documenting this research during the National Student Summit on February 15, 2011 at the Smithsonian's National Museum of Natural History. After the Summit, the team broadened the project's scope to include climate change education through the production of a second video. This film, We Sea Change, aims to give their local community in Wilmington an understanding of climate change, impacts on the coastal Carolina region, and how people can be part of the climate change solution. We Sea Change will be broadcast live to the Ocean Portal from the North Carolina Aquarium at Fort Fisher on Wednesday, September 28, 2011 at 7pm. There will be a panel discussion on climate change immediately following the 7pm screening. Meet the team! The Cape Fear Beach Bears: Sandy Paws for a Cause team members include students Jessica Lama, Keela Sweeney, Evan Lucas, and Dustin Chambers. They have conducted research and produced their videos under the guidance of teachers Bryan Bishop from Isaac Bear Early College High School and Megan Ennes from the North Carolina Aquarium at Fort Fisher.
Gwen Noda

Aerosols Altered Asian Monsoons - 0 views

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    Aerosols Altered Asian Monsoons Summer monsoons provide much of the water for farming on the Indian subcontinent, but the pattern of rain shifted dramatically during the last half of the 20th century. In a study appearing online 29 September in Science, researchers pin the blame on soot and other aerosols from human activities. from 1951 to 1999, central-northern India became drier while Pakistan, northwestern India, and southern India got wetter. To determine whether these changes were due to natural variability or human interference (greenhouse gases or aerosols), climate scientists Massimo Bollasina, Yi Ming, and V. Ramaswamy of the Geophysical Fluid Dynamics Laboratory/NOAA in Princeton, New Jersey, compared the history of rainfall with simulations that singled out each climate "forcing" factor to observe its impact. Although greenhouse gases would have increased rainfall over north-central India, the aerosols, they found, caused the "very pronounced drying trend," Ming says. Here's why: Under normal conditions, the northern hemisphere receives more energy from the sun from June to September; that imbalance drives the ocean-atmosphere circulation that powers the monsoons. But atmospheric aerosols shaded the northern hemisphere relative to the southern hemisphere, altering the energy balance between the two-weakening the circulation and altering where the rain falls.
Gwen Noda

Right Whales Finally Coming Home - 0 views

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    Right Whales Finally Coming Home Figure "CREDIT: MICHAËL CATANZARITI/WIKIMEDIA COMMONS" After more than 100 years, right whales have returned to their calving grounds in New Zealand, an international team of scientists reports. The 100-ton whales, known for their social frolicking and impressive acrobatic displays, were hunted to extinction in these same waters during the 19th and 20th centuries' era of industrial whaling. A small population managed to survive near remote, sub-Antarctic islands south of New Zealand. In recent years, a few dozen females found their way back to the same bays their ancestors used for bearing their young. Normally, such cultural knowledge is passed from mother to daughter, the researchers say. But the tradition had been lost, until these pioneering females began making the journey once again. Reporting in Marine Ecology Progress Series, the scientists-from Canada, the United States, Australia, and New Zealand-confirmed that some of the females had migrated from the southern islands to New Zealand by comparing the DNA in tissue samples collected from seven whales at both sites. Now that the tradition has been restored, scientists expect more whales to follow the pioneers.
Gwen Noda

Genetically Modified Salmon and Full Impact Assessment - 0 views

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    As the U.S. Food and Drug Administration (FDA) considers approving a genetically modified (GM) Atlantic salmon (Salmo salar), it faces fundamental questions of risk analysis and impact assessment. The GM salmon-whose genome contains an inserted growth gene from Pacific chinook salmon (Oncorhynchus tshawytscha) and a switch-on gene from ocean pout (Zoarces americanus)-would be the first transgenic animal approved for human consumption in the United States (1, 2). But the mechanism for its approval, FDA's new animal drug application (NADA) process (2), narrowly examines only the risks of each GM salmon compared with a non-GM salmon (2, 3). This approach fails to acknowledge that the new product's attributes may affect total production and consumption of salmon. This potentially excludes major human health and environmental impacts, both benefits and risks. Regulators need to consider the full scope of such impacts in risk analyses to avoid unintended consequences (4), yet FDA does not consider ancillary benefits and risks from salmon market expansion (2, 3), a result of what may be an overly narrow interpretation of statutes.
Gwen Noda

NSF Touts Family-Friendly Policies as Boon to Women - 0 views

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    "Scientific Workforce NSF Touts Family-Friendly Policies as Boon to Women 1. Jeffrey Mervis Young women are forever asking Meg Urry, an astrophysicist at Yale University, if it's possible "to have a successful scientific career and a family." A tenured professor with both, Urry tells them "yes." Perhaps more telling, however, is that the issue doesn't seem to interest half of her students. "I've never been asked that question by a man," she says. This week, the National Science Foundation (NSF) rolled out a set of family-friendly policies that it hopes will reduce the number of young women who jettison scientific careers because of responsibilities outside the lab. "Too many women give up because of conflicts between their desire to start a family and their desire to ramp up their careers," says John Holdren, the president's science adviser and head of the Office of Science and Technology Policy. It was a rare moment in the spotlight for the low-profile basic research agency: First Lady Michelle Obama announced the policies at a White House ceremony touting the importance of women to the nation's economic recovery and, in particular, the need to improve the proportion of women in the so-called STEM (science, technology, engineering, and mathematics) workforce. Figure View larger version: * In this page * In a new window Lending a hand. First Lady Michelle Obama applauds the work of young women in science at a White House event. "CREDIT: NATIONAL SCIENCE FOUNDATION" The new policies will allow both male and female grant recipients to defer an award for up to 1 year or receive a no-cost extension of an existing grant. NSF also hopes to increase its use of "virtual reviews" of grant proposals so that scientists don't need to travel as often to the agency's Arlington, Virginia, headquarters. The only change with any price tag attached is a new program of supplemental awards to investigators going on family leave, allowing them to hi
Gwen Noda

Could East Antarctica Be Headed for Big Melt? - 0 views

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    "The Orangeburg Scarp, a band of hard, crusty sediment teeming with tiny plankton fossils that runs from Florida to Virginia, marks an ancient shoreline where waves eroded bedrock 3 million years ago. That period, the middle Pliocene, saw carbon dioxide levels and temperatures that many scientists say could recur by 2100. The question is: Could those conditions also result in Pliocene-epoch sea levels within the next 10 to 20 centuries, sea levels that may have been as much as 35 meters higher than they are today? The answer, say climate scientists, may lie 17,000 kilometers away in East Antarctica. The East Antarctic Ice Sheet is the world's largest, a formation up to 4 km thick and 11 million km2 in area that covers three-quarters of the southernmost continent. Its glaciers were thought to sit mostly above sea level, protecting them from the type of ocean-induced losses that are affecting the West Antarctic Ice Sheet. But studies of ancient sea levels that focus on the Orangeburg Scarp and other sites challenge that long-held assumption. Not everybody believes the records from Orangeburg. But combined with several other new lines of evidence, they support the idea that parts of East Antarctica could indeed be more prone to melting than expected. "
Gwen Noda

Three Historic Blowouts - 0 views

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    Three Historic Blowouts 1. Lauren Schenkman Figure Mexico 1979 "CREDIT: NOAA" The decade from 1969 to 1979 witnessed three massive spills from offshore oil wells around the world. Here is how they compare in size and impact. IXTOC 1 The biggest well-related spill was triggered on 3 June 1979, when a lack of drilling mud allowed oil and gas to shoot up through the 3.6-km-deep IXTOC 1 exploratory well, about 80 km offshore in the southern Gulf of Mexico. The initial daily outflow of 30,000 barrels of oil was eventually reduced to 10,000 barrels. The well was finally capped more than 9 months later. Mexico's state-owned oil company, PEMEX, treated the approximately 3.5-million-barrel spill with dispersants. U.S. officials had a 2-month head start to reduce impacts to the Texas coastline. Figure North Sea 1977 "CREDIT: WALLY FONG/AP PHOTO" Ekofisk The first major spill in the North Sea resulted in the release of 202,000 barrels of oil about 250 km off the coast of Norway. The 22 April 1977 blowout caused oil to gush from an open pipe 20 m above the sea surface. The well was capped after a week. Between 30% and 40% of the spill evaporated almost immediately. Rough waters broke up the slick before it reached shore. Figure Santa Barbara 1969 "CREDIT: BETTMANN/CORBIS" Santa Barbara A blown well 1 km below the sea floor and 9 km off the coast of Santa Barbara, California, spewed out a total of 100,000 barrels of oil. The initial eruption occurred on 28 January 1969, and the well was capped by mud and cement on 7 February, but the pressure forced oil through sea floor fissures until December. The oil contaminated 65 km of coastline. At least 3700 birds are known to have died, and commercial fishing in the area was closed until April.
Gwen Noda

YouTube - Time Lapse from Space - Earth - 0 views

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    "Time lapse footage taken by Oregon State University alum Don Pettit during his time on the International Space Station. This one shows Earth from day to night. Watch the other eight time lapse videos from space http://www.youtube.com/view_play_list... science"
Gwen Noda

Back from the dead: 800,000-year-old plankton - CBS News - 0 views

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    Not really back from the dead: A single-celled alga that went extinct in the North Atlantic Ocean about 800,000 years ago has returned after drifting from the Pacific through the Arctic thanks to melting polar ice. And while its appearance marks the first trans-Arctic migration in modern times, scientists say it signals something potentially bigger.
Gwen Noda

Experts Agree Global Warming Is Melting the World Rapidly - 0 views

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    Experts Agree Global Warming Is Melting the World Rapidly Richard A. Kerr Forty-seven glaciologists have arrived at a community consensus over all the data on what the past century's warming has done to the great ice sheets: a current annual loss of 344 billion tons of glacial ice, accounting for 20% of current sea level rise. Greenland's share-about 263 billion tons-is roughly what most researchers expected, but Antarctica's represents the first agreement on a rate that had ranged from a far larger loss to an actual gain. The new analysis, published on page 1183 of this week's issue of Science, also makes it clear that losses from Greenland and West Antarctica have been accelerating, showing that some ice sheets are disconcertingly sensitive to warming.
Gwen Noda

Science Magazine: Sign In - 0 views

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    Warming and Melting Mass loss from the ice sheets of Greenland and Antarctica account for a large fraction of global sea-level rise. Part of this loss is because of the effects of warmer air temperatures, and another because of the rising ocean temperatures to which they are being exposed. Joughin et al. (p. 1172) review how ocean-ice interactions are impacting ice sheets and discuss the possible ways that exposure of floating ice shelves and grounded ice margins are subject to the influences of warming ocean currents. Estimates of the mass balance of the ice sheets of Greenland and Antarctica have differed greatly-in some cases, not even agreeing about whether there is a net loss or a net gain-making it more difficult to project accurately future sea-level change. Shepherd et al. (p. 1183) combined data sets produced by satellite altimetry, interferometry, and gravimetry to construct a more robust ice-sheet mass balance for the period between 1992 and 2011. All major regions of the two ice sheets appear to be losing mass, except for East Antarctica. All told, mass loss from the polar ice sheets is contributing about 0.6 millimeters per year (roughly 20% of the total) to the current rate of global sea-level rise.
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